how to fix a formatting corruption of my calc files by excel

I am using Libre Office Version: Build ID: 420m0(Build:3)
My OS is Linux Mint 17 Rebecca Cinamon installed side by side.
MY MS OS is Win-7 Home Edition.
My computer is dual core Intel processor with 4Gb ram
I opened two calc files with MS Office Excel pro and edited and saved ONE of the files, I then closed Excel and re-booted to Linux. When I opened the two calc files again with Libre Office, one was corrupted with dots, (periods) spaced just a bit wider than my cell height and about the same spacing along the row. Their spacing “format” is independent of my cell height or length. This corruption appears in new files opened with Libre office. As stated previously, I had opened two files with excel and saved only one with excel. The second file open with excel, but never edited or saved was not corrupted. Now even new files created with Libre Office contain this corruption, (virus). How do I remove this virus from Libre Office?

The uniform “dots” are a setup election within Libre Office Calc. To remove the “dots” do the following;
From the menu select Tools + Options + Libre Office Calc + Grid - and de-select “snap to grid” also “Visible grid”